Spatial structure of vegetation of the forb-feathergrass steppe subzone in the Southern West-Siberian Plain (Northern Kulunda)

The standard sample area of 50 km² for large-scale vegetation mapping has been taken on the water-shad of Bagan and Karasu rivers. Relief of the region is formed byelongate hills («griva») and depressions between them. The hills are occupied by arable land whereas the depressions are covered by natural vegetation.

The main reguliarities of vegetation cover are presented on the vegetation map at 1 : 100 000 scale (fig. 1). 25 of the 31 numbers of the legend represent heterogeneous vegetation; these are territorial units, combinations sensu S. A. Gribova and T. I. Isachenko (1972) or phytocoenochoras after V. B. Sochava (1979). All the heterogeneous territorial units are subdivided into two categories – microcombinations and mezo-combinations. While the formers include complexes and microzonal series, the latters include ecological series and combinations. The inner diversity of territorial units is reflected in more details on the key plot of 100 x 100 m showing the vegetation of a small interhill depression with salt-rich soils. Through the comparison of different scale schematic pictures – 1 : 1000 (fig. 2a), 1 : 10 000 (fig. 2б), 1 : 50 000 (fig. 2в) – the process of generalization of territorial unit structures is illustrated, starting from the complexes, proceeding to microzonal series and, finally, to mezocombinations. The main territorial unit for large-scale and middle-scale maps is mezocombinations.